chr6-145635323-G-C

Position:

• chr6-145635323-G-C

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM1 PM2 PP3

The NM_005670.4(EPM2A):​c.640C>G​(p.Pro214Ala) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: EPM2A NM_005670.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 6.43

Genes affected

EPM2A (HGNC:3413): (EPM2A glucan phosphatase, laforin) This gene encodes a dual-specificity phosphatase and may be involved in the regulation of glycogen metabolism. The protein acts on complex carbohydrates to prevent glycogen hyperphosphorylation, thus avoiding the formation of insoluble aggregates. Loss-of-function mutations in this gene have been associated with Lafora disease, a rare, adult-onset recessive neurodegenerative disease, which results in myoclonus epilepsy and usually results in death several years after the onset of symptoms. The disease is characterized by the accumulation of insoluble particles called Lafora bodies, which are derived from glycogen. [provided by RefSeq, Jan 2018]

ACMG classification

Verdict is Uncertain_significance. Variant got 5 ACMG points.

• PM1: In a domain Tyrosine-protein phosphatase (size 167) in uniprot entity EPM2A_HUMAN there are 10 pathogenic changes around while only 1 benign (91%) in NM_005670.4
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.791

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
EPM2A	NM_005670.4	c.640C>G	p.Pro214Ala	missense_variant	3/4	ENST00000367519.9	NP_005661.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
EPM2A	ENST00000367519.9	c.640C>G	p.Pro214Ala	missense_variant	3/4	1	NM_005670.4	ENSP00000356489	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Progressive myoclonic epilepsy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Feb 28, 2017

In summary, this variant is a novel missense change that is not predicted to affect protein function. There is no indication that it causes disease, but the available evidence is currently insufficient to prove that conclusively. Therefore, it has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Deleterious"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C25". The alanine amino acid residue is found in multiple mammalian species, suggesting that this missense change does not adversely affect protein function. These predictions have not been confirmed by published functional studies. This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with a EPM2A-related disease. This sequence change replaces proline with alanine at codon 214 of the EPM2A protein (p.Pro214Ala). The proline residue is highly conserved and there is a small physicochemical difference between proline and alanine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Uncertain	0.14	D
BayesDel_noAF	Uncertain	-0.030
CADD	Benign	22
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.44	.;T;.;.;.;.;.;.;.
Eigen	Uncertain	0.29
Eigen_PC	Uncertain	0.35
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Benign	0.74	T;T;.;T;.;.;.;.;T
M_CAP	Uncertain	0.19	D
MetaRNN	Pathogenic	0.79	D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	0.82	D
MutationAssessor	Uncertain	2.1	.;M;.;M;.;M;.;.;.
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.48	T
PROVEAN	Benign	-1.8	.;N;.;.;.;.;.;.;.
REVEL	Pathogenic	0.67
Sift	Benign	0.20	.;T;.;.;.;.;.;.;.
Sift4G	Uncertain	0.019	.;D;.;D;T;.;.;.;.
Polyphen		0.96, 0.89	.;D;.;P;.;P;.;.;.
Vest4		0.42, 0.49, 0.46
MutPred		0.62		.;Loss of glycosylation at P214 (P = 0.0421);.;Loss of glycosylation at P214 (P = 0.0421);.;Loss of glycosylation at P214 (P = 0.0421);.;.;.;
MVP		0.96
MPC		0.68
ClinPred		0.86	D
GERP RS		5.0
gMVP		0.58

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs1278542056; hg19: chr6-145956459;